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Monday, 20 October 2008

Scientists have reported a fascinating discovery in a rock fissure in the Mponeng gold mine near Johannesburg nearly 3km below the earth's surface. They found rod-shaped bacteria, named Desulforudis audaxviator, in water extracted from a rock fissure.

This bacterium exists in total darkness with no oxygen and in a temperature of 60 degrees celsius. However the most important aspect of this discovery, according to researchers at the Lawrence Berkley National Laboratory in California, is that the bacterium lives in its own ecosystem - the first known species to do so.

"One question that has arisen when considering the capacity of other planets to support life is whether organisms can exist independently, without access even to the sun," says Dylan Chivian, the bioinformatics lead scientist at the Joint BioEnergy Institute in Berkeley, California, who studied the gene samples found in the fissure water.

"The answer is yes, and here's the proof. It's sort of philosophically exciting to know that everything necessary for life can be packed into a single genome." (quoted in the Sunday Independent 19 Oct, page 5)

It is believed that this kind of organism could survive below the surface of Mars as it gets its energy from hydrogen and sulphate produced by the radioactive decay of uranium. It is also believed that it builds its organic molecules by itself out of water, inorganic carbon and nitrogen from ammonia in the surrounding rocks and fluid.

Another fascinating aspect of this bacterium is that it can't live in oxygen which suggest that it hasn't been exposed to pure oxygen for a very long time, perhaps millions of years. Scientists believe that the water the bacterium lives in has not seen light for more than 3 million years!

D audaxviator's name comes from Jules Verne's Journey to the Centre of the Earth, in which a message in Latin deciphered by Professor Lidenbrock, Verne's protagonist, reads in part, "descende, Audax viator, et terrestre centrum attinges". It means "descend, Bold traveller, and attain the centre of the Earth".